1. Field of the Invention
The present invention pertains to the art of laundry appliances and, more particularly, to a system for detecting the relative attachment of hot and cold inlet water hoses to a washing machine.
2. Discussion of the Prior Art
When initially installing a washing machine, it is necessary to connect water inlet hoses to hot and cold water supply lines. Since a washing machine can be utilized in a wide range of water temperature settings, typically based on at least hot, cold and warm temperature selections, the ability of the machine to accurately establish the desired wash temperature can be severely compromised if the inlet hoses are inadvertently connected to the inlet water lines in reverse. That is, if the cold inlet hose is attached to the hot water supply and the hot inlet hose is attached to the cold water supply, establishing a desired wash water temperature can be impossible.
To address this problem, it has heretofore been proposed to incorporate a temperature sensor in each of the inlet flow paths to a washing machine in order to sense a temperature of each inlet stream. Based on these sensed temperatures, the proportion of each of the streams needed to be admitted into the machine in order to establish the desired temperature is calculated and valves associated with each of the inlet streams are correspondingly controlled. In this sense, the actual hook-up arrangement is irrelevant since the temperatures for the streams are separately calculated and utilized in establishing the resulting inlet water stream. Examples of such known arrangements are represented by the disclosures in U.S. Pat. Nos. 4,406,401 and 4,528,709.
With such known systems, multiple temperature sensors are needed. Obviously, this adds to the associated cost and complexity of the system. In addition, the sensed temperatures are keyed to absolute values. That is, the established water supply is calculated based on absolute values of the temperatures sensed from the two water supplies. This reliance on directly sensed water temperatures is considered to be less than desirable for various reasons. For instance, the actual temperature of one or more of the water supplies can vary significantly from the beginning to end of a fill operation or between fill operations. Even if the temperature was continually taken, the response of such known temperature sensors is considered to be too slow to assure an accurate fill temperature. This problem is heightened in situations wherein a relatively low amount of fill water is needed for a desired washing operation.
For at least the reasons presented above, there exists a need in the art for an improved system for detecting the relative attachment of hot and cold inlet water hoses to a washing machine in order that an accurate fill temperature can be established for a desired washing operation selected by a user of the machine. In addition, there exists a need for a system of the type discussed above which will determine the actual hose hook-up arrangement and store this information for future use, while also verifying the status of the hook-up for subsequent washing operations.
The present invention is directed to a system for detecting the relative attachment of hot and cold inlet water hoses to a washing machine. In accordance with the invention, the temperature of at least one of the hot and cold water inputs is monitored to determine if the temperature is increasing or decreasing. Once the hoses are correctly identified, this information is stored in permanent memory of the machine. This stored information is preferably checked during subsequent washing operations, preferably during any cold fill.
In accordance with the most preferred embodiment of the invention, an initial temperature reading is taken. Thereafter, the cold water valve is opened. After a predetermined time period has elapsed, the inlet water temperature reading is taken. It is then determined whether this inlet temperature is greater than each of a preset temperature and the initial temperature. If either of these determinations is not met, another inlet temperature reading is taken after waiting an additional time period. This cycle continues until the inlet temperature reading meets both of these requirements.
In the next stage, the hot water valve is opened and the cold water valve is closed. A new initial temperature reading is taken and saved as a switchpoint temperature. After waiting a predetermined time period, an inlet temperature is taken. Thereafter, it is determined whether the inlet temperature is less than the switchpoint temperature minus a predetermined temperature value, such as ten degrees Fahrenheit. If a less than determination is reached, the established hot and cold water valve designations are reversed and saved in memory. On the other hand, if a less than determination is not reached, a determination is made as to whether the inlet temperature is greater than the switchpoint temperature plus the predetermined temperature value. If the answer is no, then a new inlet temperature reading is taken after a time delay. This new inlet temperature reading is again sensed and compared to the switchpoint temperature in the manner set forth above. This sequence continues until one of the xe2x80x9cless thanxe2x80x9d or xe2x80x9cgreater thanxe2x80x9d determinations is reached. If the inlet temperature is determined to be greater than the switchpoint temperature plus the predetermined temperature value, it is realized that the wrong valve is on such that the cold valve is again opened and the hot valve closed.
This information is preferably checked periodically. In accordance with the most preferred form of the invention, the information is checked every cycle that has a cold fill. In any event, additional objects, features and advantages of the present invention will become more readily apparent from the following detailed description of a preferred embodiment when taken in conjunction with the drawings wherein like reference numerals refer to corresponding parts in the several views.